use sort.Slice to sort the tags in the handshake message

sort.Slice was added in Go 1.8. Now that we've dropped support for Go
1.7, we can make use of it.

internal/utils/utils_test.go

@@ -3,7 +3,6 @@ package utils
 import (
 	"bytes"
 	"io"
-	"sort"
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -194,10 +193,4 @@ var _ = Describe("Utils", func() {
 			Expect(err).To(HaveOccurred())
 		})
 	})
-
-	It("sorts uint32 slices", func() {
-		s := Uint32Slice{1, 5, 2, 4, 3}
-		sort.Sort(s)
-		Expect(s).To(Equal(Uint32Slice{1, 2, 3, 4, 5}))
-	})
 })